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ATP-dependent potassium channels in the cardiac cell
J Hescheler1, B Belles, G Trube
1II. Physiologisches Institut, Uni. d. Saarlandes, Homburg/Saar.
Biomedica Biochimica Acta
|January 1, 1987
Summary
Researchers investigated ATP-dependent potassium channels in guinea pig heart cells. They found that intracellular ATP inhibits these channels, a finding confirmed by tolbutamide
Area of Science:
- Cardiovascular Physiology
- Ion Channel Electrophysiology
- Pharmacology
Background:
- The ATP-dependent potassium (K+) channel plays a crucial role in cardiac function.
- Understanding its regulation is vital for cardiac health and disease management.
Purpose of the Study:
- To investigate the properties of the ATP-dependent K+ channel in guinea pig ventricular myocytes.
- To determine the effects of intracellular ATP and tolbutamide on this specific ion current.
Main Methods:
- Utilized patch-clamp techniques, including whole-cell and single-channel recordings.
- Applied intracellular ATP and the calcium chelator EGTA to assess current modulation.
- Tested the inhibitory effect of tolbutamide on the ATP-dependent K+ current.
Main Results:
- Observed an increase in time-independent K+ outward current during prolonged whole-cell recordings.
- Demonstrated that intracellular ATP (3-20 mM) inhibits this outward current.
- Confirmed ATP's inhibitory effect in single-channel experiments.
- Showed that tolbutamide specifically inhibits the ATP-dependent K+ current with an IC50 of 0.4 mM.
Conclusions:
- The ATP-dependent K+ channel in guinea pig ventricular myocytes is inhibited by intracellular ATP.
- Tolbutamide acts as a specific inhibitor of this cardiac ATP-dependent K+ current.
- These findings contribute to understanding ion channel regulation in the heart.